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Updated: Feb 5, 2026
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Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry
Published on: July 20, 2016
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Applications of 2-(Bromoalkyl)Benzaldehydes in Bioconjugation
August Ulstrup Ring1, Martin Frandsen1, Fie Noer1
1Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark.
Bioconjugate Chemistry
|February 3, 2026
Summary
New aldehyde reagents enable efficient bioconjugation. These 2-(bromoalkyl)benzaldehydes react directly with amines, offering stable and versatile labeling for proteins and oligonucleotides in therapeutics and imaging.
Area of Science:
- Chemical Biology
- Organic Chemistry
- Bioconjugation Chemistry
Background:
- Aldehyde-based bioconjugation is an alternative to N-hydroxysuccinimide (NHS) esters for amine modification.
- Existing methods often require auxiliary reagents or have limited stability.
Purpose of the Study:
- To develop versatile and stable aldehyde-based reagents for bioconjugation.
- To explore their application in labeling proteins, oligonucleotides, and antibodies.
Main Methods:
- Synthesis and application of 2-(bromoalkyl)benzaldehydes for direct reaction with primary amines.
- Utilizing intramolecular cyclization to form stable isoquinolinium intermediates.
- Incorporating alkyne or azide handles for click chemistry (CuAAC and SPAAC).
Main Results:
- 2-(bromoalkyl)benzaldehydes react directly with primary amines in aqueous media without catalysts.
- Ortho-bromoethyl analogues form stable isoquinolinium intermediates with improved aqueous stability over NHS esters.
- Demonstrated successful labeling of proteins, oligonucleotides, and antibodies, including a one-pot copper-free DNA-antibody conjugation.
Conclusions:
- A modular and reagent-economical platform for mild, efficient, and durable bioconjugation.
- Broadly applicable strategy for targeted therapeutics, molecular imaging, and nanoscale engineering.
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